Depending on the application where it is used, sensing the voltage of a battery can be important for a number of reasons. For example, in the case of electric or hybrid electric vehicles, which may utilize high-voltage batteries made up of many smaller battery cells, knowing the voltage in each cell or a group of cells can be important for many control functions, including the control of regenerative braking decisions, whether to propel the vehicle using an engine or electric motor, and how to control the various electrical loads within the vehicle—e.g., air conditioning—just to name a few. In applications such as these, an electrical conductor, such as a wire may be used to carry voltage information from a cell or cells to a controller in the vehicle. Under ordinary circumstances, such a wire will carry only a low current load, and therefore may be of a relatively small gauge.
If two or more of these wires are shorted together, the battery cells they are connected to will also be shorted together, and large amounts of current could then be drawn through these wires, which may not be equipped to handle such a load. Protecting the wires through the addition of an in-line current protector, such as a fuse, is generally not a good solution to the potential problem. First, there may be industry design standards that prohibit using in-line components for these “sensing wires”. Moreover, splicing components into a small-gauge sensing wire creates new problems, such as supporting the wire with the additional weight of the component so as to not overstress the two splices where the wire connects to the component. Therefore, there is an ongoing problem throughout the life of the vehicle with ensuring the reliability of the splices—e.g., if one of them becomes disconnected or partially disconnected, erroneous voltage information or no information may be transmitted to the controller.
Therefore, a need exists for a system and method for protecting voltage sensing wires from unexpectedly large current loads, without relying on in-line fuse protection.